CN113443980B

CN113443980B - Can be used for heavy metal Cu2+Preparation and application of detected rare earth fluorescent material

Info

Publication number: CN113443980B
Application number: CN202110755116.6A
Authority: CN
Inventors: 宁张磊; 杨洁; 杨婷
Original assignee: Sichuan Normal University
Current assignee: Sichuan Normal University
Priority date: 2021-07-05
Filing date: 2021-07-05
Publication date: 2022-07-19
Anticipated expiration: 2041-07-05
Also published as: CN113443980A

Abstract

The invention relates to a Cu-based alloy²⁺Preparation and application of the rare earth fluorescent material for ion detection: s1, selecting raw materials, terbium nitrate hexahydrate and mucic acid; s2, dissolving mucic acid in distilled water and stirring; s3, adding the potassium hydroxide solution into the solution obtained in the S2, and stirring; s4, adding the terbium nitrate hexahydrate solution into the solution obtained in the S3, and stirring; s5, stopping stirring, standing for aging, centrifugally collecting white precipitate, washing, and drying to obtain a white sample of the rare earth metal organic framework fluorescent material (rare earth fluorescent material for short); s6, applying the obtained rare earth fluorescent material to heavy metal Cu²⁺And (4) detecting ions. The rare earth fluorescent material is a rare earth metal organic framework fluorescent material prepared by a simple method, and can be used for quantitatively detecting heavy metal Cu in water²⁺The presence of ions.

Description

Cu capable of being used for heavy metal2+Preparation and application of detected rare earth fluorescent material

Technical Field

The invention relates to the technical field of preparation of rare earth fluorescent materials, in particular to a rare earth fluorescent material for Cu²⁺Preparation and application of rare earth metal organic framework fluorescent material for ion detection.

Background

Copper ion (Cu)²⁺) As one of the trace elements essential to human body, it is involved in the synthesis of various biological enzymes as an auxiliary group. Copper deficiency causes anemia, bone changes, coronary heart disease, etc., however, excessive copper ion destroys the balance between cells, and also causes loss of the body and disorder of physiological functions, resulting in a series of neurodegenerative diseases: such as alzheimer's disease, wilson's disease and parkinson's disease; in addition, it can also cause polyneuritis, neurasthenia syndrome, and abnormal liver function. The limits of the World Health Organization (WHO) and the United states Environmental Protection Agency (EPA) on copper ions in water are 2 mg/L and 1.3 mg/L respectively, and the concentration of copper in domestic drinking water is not more than 1.0 mg/L according to the regulations of China. Therefore, the method for detecting the copper ions is established with high efficiency, rapidness, convenience and sensitivity, and has very important significance in the aspects of human health, environmental monitoring and the like. To date, various methods have been reported for detecting heavy metal copper ionsThe methods of (3) include atomic absorption spectrometry, colorimetry, volumetric analysis, instrumental analysis, ion chromatography, electrochemical analysis, and the like. In contrast, stripping voltammetry, which is an electrochemical analysis method, has attracted much attention because of its high sensitivity and high selectivity. However, the detection is carried out by stripping voltammetry, a mercury film needs to be enriched on the surface of the electrode in advance, and the pretreatment process is complicated. Other detection methods also require expensive instruments and complicated operations, thereby limiting their widespread use. Compared with the methods, the fluorescence sensing has a series of advantages of rapidness, low loss, convenience, good selectivity, high sensitivity, good repeatability and the like.

The rare earth metal organic framework has strong luminous performance, and the development of a new rare earth organic framework material and the expansion of the application field thereof become hot contents of current research. Currently, an increasing group of subjects is conducting research on the material, and metal organic framework materials with various structures and properties have been synthesized. However, most of the materials reported in the literature have the disadvantages of slow response time, low sensitivity, poor anti-interference performance and the like, and meanwhile, the fluorescence intensity of the material is easily influenced by other factors, so that the detection result is easy to be inaccurate, and the existence of heavy metal copper ions is difficult to be accurately detected.

Disclosure of Invention

In order to solve the above problems, it is an object of the present invention to provide a Cu alloy useful for heavy metals²⁺Rare earth fluorescent material for ion detection.

In order to achieve the purpose, the invention provides the following technical scheme: cu capable of being used for heavy metal²⁺The preparation and application of the rare earth fluorescent material for ion detection comprise the following steps:

s1, selecting raw materials, terbium nitrate hexahydrate and mucic acid;

s2, dissolving mucic acid in distilled water and stirring;

s3, adding the potassium hydroxide solution into the solution obtained in the S2, and stirring;

s4, adding the terbium nitrate hexahydrate solution into the solution obtained in the S3, and stirring;

s5, stopping stirring, standing for aging, centrifugally collecting white precipitate, washing, and drying to obtain a white sample of the rare earth metal organic frame;

s6, applying the obtained rare earth fluorescent material to heavy metal Cu²⁺And (4) detecting ions.

Preferably, the step S2 is performed at room temperature for 10 minutes, and the step S3, S4 are performed at room temperature for 30 minutes;

preferably, the standing and aging time in the step S4 is 24 hours, the drying temperature is 55 ℃, and the time is 12 hours;

preferably, 2mg of the sample is weighed in a centrifuge tube in the step S6, 5mL of distilled water is added, and 1mL of 1 × 10 is added^-2 mol L^-1Cu of (2)²⁺Solution, ultrasonic treatment for 30 minutes;

preferably, the detection is selectivity, interference resistance and sensitivity.

Compared with the prior art, the invention has the beneficial effects that: the invention selects the rare earth metal terbium ion (Tb) which is one of the most important fluorescent activators³⁺) The rare earth metal organic framework material is formed by taking muconic acid with polyhydroxy as a raw material, has typical fluorescence characteristic, and can more accurately detect heavy metal Cu²⁺The presence of ions.

Drawings

FIG. 1 is a schematic diagram of the preparation and application of the rare earth fluorescent material of the present invention;

FIG. 2 is a XRD spectrum of the rare earth fluorescent material prepared in the present invention and reported in the literature;

FIG. 3 is an excitation spectrum and an emission spectrum of the rare earth fluorescent material according to the present invention;

FIG. 4 shows that the rare earth fluorescent material of the present invention is immersed in 1X 10 under 298K conditions^-2The emission spectra after M different metal ions, inset is a histogram of the sample emission intensity monitored at 545 nm;

FIG. 5 shows that different metal ions and the same amount of Cu are added into the rare earth fluorescent material of the present invention²⁺A plot of fluorescence intensity of samples in aqueous dispersion in the presence of ions;

FIG. 6 shows that the rare earth fluorescent material of the present invention is added with CuCl of different concentrations at 545 nm₂In aqueous solutionEmission spectrum (a), fluorescence intensity and [ Cu ]²⁺]Linear fit graph (b);

FIG. 7 shows the rare earth fluorescent material of the present invention containing Cu at different concentrations²⁺Soaking the HEPES in a HEPES buffer aqueous solution for 24 hours to obtain an emission spectrum;

FIG. 8 shows the rare earth fluorescent material of the present invention at different concentrations of Cu²⁺Fluorescence decay profile under ions.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments only disclose a part of the embodiments, but not all the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example one

Referring to FIG. 1, a method for preparing Cu as heavy metal²⁺The preparation and application of the rare earth fluorescent material for ion detection comprise the following steps:

s1, selecting raw materials, terbium nitrate hexahydrate and mucic acid;

s2, dissolving mucic acid in distilled water and stirring;

s5, stopping stirring, standing for aging, centrifugally collecting white precipitate, washing, and drying to obtain a white sample of the rare earth fluorescent material;

s6, applying the obtained rare earth fluorescent material to heavy metal Cu²⁺Detection of (3).

Further, the step S2 is performed at room temperature for 10 minutes, and the steps S3 and S4 are performed at room temperature for 30 minutes;

further, in the step S5, the standing time is 24 hours, the baking temperature is 55 ℃, and the time is 12 hours;

further, in the step S62mg of the sample was weighed into a centrifuge tube, 5mL of distilled water was added, and 1mL of 1X 10 solution was added^-2 molL^-1Cu of (2)²⁺Solution, ultrasonic treatment for 30 minutes;

further, the detection is selectivity, anti-interference performance and sensitivity.

Wherein, the prepared rare earth fluorescent material is used for heavy metal Cu²⁺And (3) selective testing of ions: under the condition of room temperature, 2mg rare earth fluorescent material samples are respectively dispersed to the concentration of 10^-2 molL^-1Containing different metal ions, e.g. Sr²⁺, Ba²⁺, Mg² ⁺, Mn²⁺, Na⁺, Ca²⁺, K⁺, Zn²⁺, Cr³⁺, Ni²⁺, Co²⁺, Cu²⁺In an aqueous solution of (a). The mixture was then sonicated for 30 minutes to form a homogeneous stable solution, and the solution was subjected to fluorescence testing.

The prepared rare earth fluorescent material is used for Cu in the presence of different metal ions²⁺Interference immunity test for detection of ions: at room temperature, respectively dispersing 2mg of rare earth fluorescent material in Sr²⁺, Ba²⁺, Mg²⁺, Mn²⁺, Na⁺, Ca² ⁺, K⁺, Zn²⁺, Cr³⁺, Ni²⁺, Co²⁺Performing ultrasonic treatment for 30 minutes in the aqueous solution of (2) and then performing a fluorescence test; then 2mg of rare earth fluorescent material is dispersed in heavy metal Cu²⁺An aqueous solution of ions, then separately adding Sr²⁺, Ba²⁺, Mg²⁺, Mn²⁺, Na⁺, Ca²⁺, K⁺, Zn²⁺, Cr³⁺, Ni²⁺, Co²⁺Then the mixture was sonicated for 30 minutes to form a homogeneous stable solution, and finally the solution was subjected to fluorescence testing.

Prepared rare earth fluorescent material to heavy metal Cu²⁺Sensitivity test of ion detection: by measuring different concentrations of heavy metal Cu²⁺The fluorescence intensity of the ions in the aqueous solution is used for realizing the calculation of the experimental sensitivity. Adding 2mg of rare earth fluorescent material sample into different samplesConcentration of heavy metal Cu²⁺Ion (0, 10)^-4，5×10^-4，10^-3，5×10^-3，10^-2，5×10^-2And 10^-1molL^-1) In the water solution, then the mixture is subjected to ultrasonic treatment for 30 minutes to form uniform and stable Cu containing heavy metal²⁺Ionic solutions and finally the solutions were tested for fluorescence.

Carrying out structural characterization on a sample, wherein the sample is a rare earth metal organic framework material:

PXRD spectrogram analysis: FIG. 2 shows the powder X-ray diffraction spectrum showing the diffraction peaks of the synthesized sample of the rare earth metal organic framework material and Tb (C) reported in the literature₆H₈O₈)_1.5·5H₂The crystal diffraction peaks of O correspond to each other. The experimental result shows that the obtained rare earth fluorescent material and the reference single crystal material are in the same crystal phase.

Furthermore, the performance of the rare earth fluorescent material is characterized.

Fig. 3 shows an excitation spectrum and an emission spectrum of the rare earth fluorescent material. According to FIG. 3, when the excitation spectrum of the rare earth fluorescent material is monitored at room temperature at 545 nm, it can be seen that the excitation spectrum has a strongest band at 227 nm due to Tb³⁺And O^2-Charge transfer zone (CTB) in between. Other sharp peaks, including those of 250-400 nm, are due to ligand-to-Tb³⁺The 4f-4f transition of the ion. This result indicates that Tb³⁺The ions are excited by host absorption in nature. After excitation at 227 nm, a plurality of clear straight lines appear in the emission spectrum (EM) of the sample at 450-700 nm, and the clear straight lines respectively come from Tb³⁺Is/are as follows⁵D₄→⁷F₆(489 nm)、⁵D₄→⁷F₅(545 nm)、⁵D₄→⁷F₄(587 nm)、⁵D₄→⁷F₃(621 nm), the strongest emission is at 545 nm, resulting in a green emission.

Example two

The rare earth fluorescent material is used as a fluorescent probe for detecting heavy metal Cu²⁺Ions.

And (3) selectivity:

FIG. 4 shows that the rare earth fluorescent material is immersed in 1X 10 under 298K condition^-2The emission spectra after M different metal ions are shown as a bar graph of the sample emission intensity monitored at 545 nm. The rare earth fluorescent material has excellent luminescence property, so that the rare earth fluorescent material can be applied to common metal ion Sr²⁺、Ba²⁺、Mg²⁺、Mn²⁺、Na⁺、Ca²⁺、K⁺、Zn²⁺、Cr³⁺、Ni²⁺、Co²⁺、Cu²⁺The detection aspect of (2) has potential application value. FIG. 4 shows rare earth fluorescent material at 298K, 1 × 10^-2M emission spectra after immersion in various metal ions. The results show that Sr²⁺、Ba²⁺、Mg²⁺、Mn²⁺、Na⁺、Ca²⁺、K⁺、Zn²⁺、Cr³⁺、Ni²⁺、Co²⁺The influence of plasma metal ions on the photoluminescence intensity of the rare earth fluorescent material is not obvious, and the Cu²⁺The addition of (a) significantly reduces the photoluminescence intensity; the rare earth fluorescent material can be more intuitively seen from the inset²⁺Excellent selectivity of (2). These results indicate that the rare earth fluorescent material emits light by Cu²⁺Ion selective quenching, rare earth fluorescent material to Cu²⁺The ions have high selective and specific recognition capability.

Anti-interference performance:

as shown in FIG. 5, the emission intensity value of the rare earth fluorescent material hardly changed when a single metal ion was added, and the same amount of Cu was added²⁺Ions and different metal ions are added into the aqueous dispersion of the rare earth fluorescent material, and the fluorescence intensity ratio of the rare earth fluorescent material is greatly reduced. This indicates when other common metal ions are associated with Cu²⁺When ions coexist, the influence on the luminous intensity of the rare earth fluorescent material is very limited, and the rare earth fluorescent material has a very limited effect on metal Cu²⁺The detection of ions has strong anti-interference capability.

Sensitivity:

FIG. 6a shows that the rare earth fluorescent material is added with CuCl of different concentrations₂Aqueous solution, fluorescence intensity at 545 nm; FIG. 6b is the fluorescence intensity vs. [ Cu ]²⁺]Is performed by linear fitting. As can be seen from FIG. 6a, in Cu²⁺The concentration is in the range of 0.1-100 mM, and the luminous intensity of the rare earth fluorescent material is seriously dependent on Cu²⁺The concentration of the ions. Fluorescence intensity as expected with Cu²⁺The increase in ion concentration decreases. When Cu²⁺When the ion concentration is 0.001 mM, the emission intensity is reduced by nearly half; when the concentration was increased to 10 mM, the emission intensity was almost completely quenched, indicating that the rare earth fluorescent material was responsible for Cu in aqueous solution²⁺Ion recognition has a high sensitivity. In order to more visually represent the rare earth fluorescent material to Cu²⁺Ion sensitivity, fluorescence intensity and [ Cu ]²⁺]The linear relationship of (A) can be fitted to the Stern Volmer equation as: i is₀/I-1= K_SV [Cu²⁺]-0.8382, wherein I₀And I is respectively the introduction of Cu²⁺The luminous intensity before and after the ion; [ M ] A]Is Cu²⁺The molar concentration of the ions; k is_SVIs the Stern Volmer constant, i.e., the quenching constant. As can be seen from the experimental data of FIG. 6b, the average K calculated by the curve equation_SVUp to 3.8 x 10³The linear correlation coefficient is 0.9933. Meanwhile, we also investigated the rare earth fluorescent material for Cu²⁺Detection limit of ion recognition. Results of fluorescence tests through 21 blank samples, according to the LOD standard in IUPAC:

wherein S_bIs the standard deviation of the luminescence intensity of the rare earth fluorescent material dispersed in deionized water (N = 21). F₀Is the fluorescence intensity of the material at 545 nm, F₁Is F₀Average value of (a); s is the slope of the linear relationship. The detection limit was calculated to be 0.667. mu.M. The result is obviously lower than that of Cu in drinking water regulated by the World Health Organization (WHO), the United states Environmental Protection Agency (EPA) and the national standard of China²⁺The limit value of the content indicates that the material can be used for Cu in water body²⁺Of ionsAnd (4) effectively detecting.

To explore such a highly selective and sensitive potential rare earth fluorescent sensor in a biological system, rare earth fluorescent sensors were immersed in simulated physiological conditions (20 mmol/L HEPES buffered water, pH = 7) with varying concentrations of Cu^{2 +}Ions, and then the luminescence of the rare earth fluorescent material crystal under simulated physiological conditions is tested. FIG. 7 shows the rare earth fluorescent materials containing different concentrations of Cu²⁺Soaking in HEPES buffer aqueous solution for 24 h. With Cu²⁺The luminous intensity of the rare earth fluorescent material is sharply reduced when the ion concentration is increased, when Cu is used²⁺When the concentration is increased to 0.01 mol/L, the luminescence of the rare earth fluorescent material is almost completely quenched. In conclusion, the fluorescence performance of the rare earth fluorescent material under physiological conditions is similar to that of the rare earth fluorescent material in aqueous solution, so that the rare earth fluorescent material can be used as Cu in a promising biological system²⁺The luminescence sensor of (1).

FIG. 8 shows the rare earth fluorescent material in Cu²⁺Fluorescence decay curves tested at different concentrations of ions. Investigation of Cu by fluorescence decay time²⁺The concentration has a quenching effect on the luminescence of the rare earth fluorescent material. Tb in rare-earth fluorescent material³⁺(⁵D₄→⁷F₅) The decay curve of (a) can be fitted to a single exponential equation and the equation can be solved: whereinI _tFor lifetime, the light emission lifetime component, A, B is a weight parameter. The results show that Cu²⁺The concentration has obvious influence on the fluorescence lifetime of the rare earth fluorescent material, and the fluorescence lifetime is reduced in different degrees within the range of 0.001-10 mM. When there is no Cu²⁺When the rare earth fluorescent material is added, the fluorescence life of the rare earth fluorescent material is 0.91 ms; when Cu²⁺At a concentration of 10 mM, the fluorescence decay time of the rare-earth fluorescent material decreases rapidly, and the lifetime is only 0.0057 ms. The result is compared with the rare earth fluorescent material to Cu with different concentrations²⁺The fluorescence intensity responses of the luminescence are consistent, indicating that static quenching is mainly used in the luminescence quenching process rather than dynamic quenching, and the sensing mechanism of the luminescence quenching process may belong to cation exchange of an organometallic framework.

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.

Claims

1. Heavy metal Cu of rare earth fluorescent material for non-disease diagnosis and treatment²⁺The application of ion detection is characterized by the following operation steps:

s1, selecting raw materials, terbium nitrate hexahydrate and mucic acid;

s2, dissolving mucic acid in distilled water, and stirring;

s4, adding a terbium nitrate hexahydrate solution into the solution obtained in the S3, and stirring;

s5, stopping stirring, standing for aging, centrifugally collecting white precipitate, washing, and drying to obtain a white sample of the rare earth metal organic framework;

s6, applying the obtained rare earth fluorescent material to heavy metal Cu2⁺Detecting ions;

the detection is selectivity, anti-interference and sensitivity.

2. The use as recited in claim 1, wherein: the step S2 is stirred for 10 minutes at room temperature, and the step S3, S4 are both stirred for 30 minutes at room temperature.

3. The use as recited in claim 1, wherein: in the step S5, the standing and aging time is 24 hours, the drying temperature is 55 ℃, and the drying time is 12 hours.

4. The use as recited in claim 1, wherein: in the step S6, 2mg of the sample is weighed into a centrifuge tube, 5mL of distilled water is added, and 1mL of 1 × 10 is added^-2mol L^-1Of Cu²⁺Solution, sonicate for 30 minutes.